The present invention relates to use of an insert for facilitating multi-component moulding of handles where a second or further component is moulded onto a core, to a handle with such an insert and to a method of moulding using such an insert.
Handles for a wide variety of objects are commonly formed of plastics materials chosen for their ease of fabrication lightness, strength and rigidity, and cost.
In recent years it has become popular to mould handles in more than one moulding step where for example the second or further moulded material is of a contrasting colour for decorative reasons, or being of a different plastics material selected for its different properties. In this case the first plastics material is moulded to form a base or core with the second or further material moulded onto or over the core.
As an example, in recent years it has become popular to provide handles with so-called xe2x80x9csoft gripsxe2x80x9d, which are regions or coverings of a soft plastics material. Elastomers are particularly effective for this purpose as they provide a high degree of resilience which assists in the firm grasping of the handle by a user. Generally the main body of the handle is formed of a plastics material which provides the required rigidity with the elastomer being moulded onto the main body in a second moulding step. The elastomer may be formed of a highly contrasting colour to the plastic of the main body whereby it is readily apparent to the user that a soft grip is provided, and the handle takes on an eye-catching and attractive appearance.
It is also often times desirable to mould the overmoulded plastics in a pattern whereby either the overmoulded plastics or the base plastics are of contrasting colour and arranged to forms words, such as for example brand names, or logos, or other decorative devices. This however leads to difficulties in the design of the mould and/or the shape of the base or core. A particular difficulty exists when trying to form shapes or letters of the alphabet which have a closed form, such as a letter xe2x80x9cO xe2x80x9d; if it is desired to have the letter formed of the base plastic and the centre of the xe2x80x9cOxe2x80x9d in the second overmoulded plastic one faces the difficulty of getting the second material to the centre of the xe2x80x9cOxe2x80x9d. One approach is to construct the mould so that a mould channel is directed at the centre of the xe2x80x9cOxe2x80x9d. Whilst this may be acceptable for a simple shape, this becomes difficult or impossible for the moulding of intricate patterns, since the fabrication of the mould becomes unduly complex and expensive. A commonly used approach with some products is to hollow out the product behind the xe2x80x9cOxe2x80x9d to the opposite thereof and provide an internal channel of communication with another surface region where the second plastic is being applied. For example, in a toothbrush handle it is desirable to have a large part of the handle with a soft grip of a soft plastics moulded onto a more rigid core, but to include a brand name on a lower part of the handle where this is formed of the plastic of the core and contrasting in colour with the soft plastic. The handle is formed with a cavity extending to the opposite side of the handle underlying the brand name whereby on moulding of the soft plastic this enters all the openings therein. This approach however places constraints on product design as the appropriate hollowed out regions have to be provided. This itself leads to additional complications in moulding of the main core.
The present invention is directed to overcoming the above drawbacks.
According to a first aspect of the present invention there is provided a mould-facilitating insert for attachment to a body of a handle onto which a plastics material is to be overmoulded, the insert defining a pattern or shape in which there is at least one element of closed form, the insert defining a bore extending through the insert which communicates with the interior of said element.
The use of such an insert allows the moulding of patterns of plastic material of contrasting colour or properties, which may include intricate patterns or words without the requirement for complex cavity shapes or internal bores to be formed in the main body.
The insert may include locating means, for example lugs for co-operation with recesses on a handle body which facilitate the correct positioning of the insert on the body.
In a further aspect of the present invention there is provided a handle for a hand-held or operated object or appliance comprising a body of a rigid material and a separate moulding insert which can be fitted onto the body and having a raised pattern or shape thereon including at least one element of closed form, the insert defining therein a bore or bores which communicates with the interior of the element of closed form.
The insert may have a width and a thickness, with the width being greater than the thickness, and the bore extending from opposite faces of the insert through the thickness, and with a lower face of the insert at which it is to be connected to the main body provided with a channel which extends laterally across the insert communicating with the bore.
The insert has an upper face formed with the raised pattern or shape and a lower face at which the insert is fitted on the main body, and a bore extending from the interior of the element of closed form to the opposite lower face where it joins a channel provided laterally across the lower face of the insert.
The invention also resides in a handle as defined above on to which a layer of plastics material, which may be a soft material such as an elastomer, is moulded on to the main body having the insert fitted therein, and over the insert with the exception of the raised pattern, whereby the plastics material extends through the bore or bores to the interior of the element of closed form.
In a still further aspect the invention resides in a method of overmoulding a layer of plastics material onto a body where the body carries a pattern or shape having at least one element of closed form, comprising the steps of (a) providing a body and a separate insert having the pattern or shape arranged in a raised manner thereon wherein the insert defines therein or with the body a bore or bores which communicate with the interior of the element of closed form; (b) fitting the insert to the body; (c) placing the body with fitted insert into a mould cavity and moulding a plastics material thereon which flows through the bore or bores to the interior of the element of closed form.